You can't tell

That doesn't mean no one else can.

The vast majority of people can't tell a male chick from a female chick, which is super important for egg farmers.

But, some people can.

And even tho they can't explain how they can tell, we know they can tell, because chicks grow up into hens and roosters. And they can tell almost instantly

Stop thinking everyone is exactly like you, no one is like anyone else, we're all snowflakes with innumerable avenues of variation.